The present invention is directed to a fitting having a dual locking swaging mechanism for securely attaching the fitting to an elastomeric tube subjected to high internal pressure.
There are many applications for a portable supply of fluid under pressure. For example, SCUBA divers and firefighters use portable, pressurized oxygen supplies. Commercial aircraft employ emergency oxygen delivery systems that are used during sudden and unexpected cabin depressurization. Military aircraft typically require supplemental oxygen supply systems as well. Such systems are supplied by portable pressurized canisters. In the medical field, gas delivery systems are provided to administer medicinal gas, such as oxygen, to a patient undergoing respiratory therapy. Supplemental oxygen delivery systems are used by patients that benefit from receiving and breathing oxygen from an oxygen supply source to supplement atmospheric oxygen breathed by the patient. For such uses, a compact, portable supplemental oxygen delivery system is useful in a wide variety of contexts, including hospital, home care, and ambulatory settings.
High-pressure supplemental oxygen delivery systems typically include a cylinder or tank containing oxygen gas at a pressure of up to 3,000 psi. A pressure regulator is used in a high-pressure oxygen delivery system to xe2x80x9cstep downxe2x80x9d the pressure of oxygen gas to a lower pressure (e.g., 20 to 50 psi) suitable for use in an oxygen delivery apparatus used by a person breathing the supplemental oxygen.
In supplemental oxygen delivery systems, and in other applications employing portable supplies of pressurized gas, containers used for the storage and use of compressed fluids, and particularly gases, generally take the form of cylindrical metal bottles that may be wound with reinforcing materials to withstand high fluid pressures. Such storage containers are expensive to manufacture, inherently heavy, bulky, inflexible, and prone to violent and explosive fragmentation upon rupture.
Container systems made from lightweight synthetic materials have been proposed. Scholley, in U.S. Pat. Nos. 4,932,403; 5,036,845; and 5,127,399, describes a flexible and portable container for compressed gases which comprises a series of elongated, substantially cylindrical chambers arranged in a parallel configuration and interconnected by narrow, bent conduits and attached to the back of a vest that can be worn by a person. The container includes a liner, which may be formed of a synthetic material such as nylon, polyethylene, polypropylene, polyurethane, tetrafluoroethylene, or polyester. The liner is covered with a high-strength reinforcing fiber, such as a high-strength braid or winding of a reinforcing material such as Kevlar(copyright) aramid fiber, and a protective coating of a material, such as polyurethane, covers the reinforcing fiber. The design described in the Scholley patents suffers a number of shortcomings which makes it impractical for use as a container for fluids stored at the pressure levels typically seen in portable fluid delivery systems such as SCUBA gear, firefighter""s oxygen systems, emergency oxygen systems, and medicinal oxygen systems. The elongated, generally cylindrical shape of the separate storage chambers does not provide an effective structure for containing highly-pressurized fluids. Moreover, the relatively large volume of the storage sections creates an unsafe system subject to possible violent rupture due to the kinetic energy of the relatively large volume of pressurized fluid stored in each chamber.
Furthermore, attaching mechanical components, such as components made from metal, including valves and gages, to polymeric or elastomeric hoses or pressure vessels can be problematic. Typically, a metal, threaded fitting is attached to the hose or pressure vessel, and gages and/or valves can be threaded onto and off of the fitting. The fitting may include a barbed projection that is inserted into the hose or pressure vessel, and a ferrule is crimped, or swaged, over the hose or pressure vessel to press the elastic material into locking engagement with the barbed projection. In such an arrangement, the hose is secured to the fitting by only the frictional engagement of the interior surface of the hose with the barbed projection. Due to the high pressure to which the fitting is exposed, however, the fitting and hose can become separated if there is slippage between the barbed projection and the interior surface of the hose.
Crimping ferrules have been formed integrally with the fitting, coaxially with the barbed projection, so as to provide a secondary mechanism by which the hose is held to the fitting, namely the frictional engagement of the interior of the crimped ferrule, which is attached to the fitting, and the exterior surface of the hose. Such integrated fitting and ferrule arrangements have been shown to provide satisfactory securement between the fitting and an elastomeric hose, but forming a ferrule that is integral with the fitting and coaxial with a barbed projection of the fitting is expensive.
Accordingly, there is a need for an inexpensive mechanical fitting that can be attached to a elastomeric hose or pressure vessel in such a manner that the fitting will not become separated from the elastomeric material, even when subjected to high internal pressures within the hose or vessel.
According to one aspect of the invention, container system for pressurized fluids comprises a pressure vessel including a plurality of hollow polymeric chambers interconnected by polymeric conduit sections positioned between adjacent ones of the plurality of hollow chambers with an end one of the conduit sections extending from an endmost one of the interconnected hollow chambers. Each of the conduit sections having a maximum interior transverse dimension that is smaller than a maximum interior transverse dimension of each of the hollow chambers. A mechanical fitting is connected to the end one of the plurality of conduit sections. The mechanical fitting comprises a body portion with a projection extending therefrom and adapted to be axially inserted into the conduit section. A ferrule is connected at one longitudinal end thereof to the body portion of the fitting and is arranged in an outwardly spaced coaxial relation with respect to the projection. The ferrule has a crimping portion constructed and arranged to be radially swaged onto a portion of the conduit section into which the projection is inserted to thereby compress the portion of the conduit section onto the projection to secure the conduit section onto the projection.
According to another aspect of the invention, a fitting assembly is adapted to be attached to an end of an elastomeric tube and comprises a body portion with a projection extending therefrom. The projection is adapted to be inserted into the end of the elastomeric tube. The body portion also includes a threaded collar adjacent the projection, and a ferrule for securing the elastomeric tube onto the projection includes a threaded opening at one longitudinal end thereof. The threaded opening of the ferrule is threaded onto the threaded collar of the body portion. The ferrule is arranged in an outwardly spaced coaxial relation with respect to the projection and has a crimping portion constructed and arranged to be radially swaged onto a portion of the elastomeric tube into which the projection is inserted to thereby compress the elastomeric tube onto the projection to secure the elastomeric tube onto the projection.
According to another aspect of the invention, a method for attaching a mechanical fitting to an end of an elastomeric tube comprises inserting a projection of a body portion of the mechanical fitting into the end of the tube, arranging a ferrule coaxially over an end of the tube into which the projection is inserted, attaching an end of the ferrule to the body portion of the fitting, and swaging a portion of the ferrule radially inwardly to radially compress the tube onto the projection to secure the tube to the projection.
Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of the specification, and wherein like reference numerals designate corresponding parts in the various figures.